Patent GB-666766-A (GB)
Title: Improvements relating to typewriting machines
IPC: B41J19/64
Filed: 1947-07-31
Abstract: 666,766. Typewriters. COXHEAD CORPORATION, R. C. July 31, 1947 [Sept. 19, 1938], No. 20747/47. Class 100 (iv). A typewriter wherein different type fonts may be employed and the platen letter-spaced according to the widths of the various type faces has (a) a track extending transversely between the bank of keys and the platen whereon two or more different font type-bar units with their operating mechanisms are slidable to bring the required unit adjacent to the key bank for operation thereby, (b) a letter-spacing mechanism comprising a series of escapement mechanisms operable in various combinations to impart to the platen carriage a movement corresponding to the sum of the movements which would be imparted by the separate actuations of the mechanisms operated and (c) a member in each type-bar-actuating mechanism to operate one or more of the escapement mechanisms when the corresponding key is depressed so that the desired letter-spacing is obtained. As shown, the machine is provided with a sub-frame 26, Fig. 1, extending laterally beyond its sides and provided with grooves in which slides a frame 34, 38. Three complete typing units of different fonts each carried by a frame 40, 42 can be detachably mounted side-byside on the frame 34, 38 by holes in the frame 40 engaging pegs 36 on the frame 34. The frame 34, 38 is moved laterally of the machine to bring the unit it is desired to use adjacent to the keyboard, in which position spring-pressed balls 48 engage recesses in the frame 34. Clamps 160 operated by cams 154 rotated by an external handle are provided for securing the frame 34 in the set position. Each unit comprises a set of type bars pivoted to a segment 44, each type-bar 16 being operated by a linkage 52, 56, 62, 64, 68, the member 68 of which has slots 70, 72 engaged by pins on levers 74, 76 respectively. The lower end of lever 76 is connected to a bar 84 slotted to engage a guide pin 86 and normally held in a rearward position by a latch 114 engaging a tooth 118 thereon. At its inner end, the bar 84 is connected to a.lever 102' by toggle links 92', 94<SP>1</SP> of which the link 92' has a projection 96'. An adjustable spring 106' is connected to the lever 102'. The lever 74 is connected to a bar 82 similar to the bar 84 and normally held rearwardly by a latch 112 engaging a tooth 120. Associated with the bar 82 are parts similar to the parts 92', 94', 102', 106'. Depression of a character key 10 operates through a lever 164 to raise a member 168 having two projections 170', 170. As shown, the projection 170 trips the latch 114 allowing the bar 84 to move forwardly under the action of the spring 106' so as to cause the type-bar 16 to be actuated to make an impression. This movement is limited by the projection 96' engaging a stop 90 and breaking the toggle. If, however, a key 172 has previously been depressed to case-shift the platen, the projection 170' would have been positioned to trip the latch 112, by a throw-over movement of member 168 caused by a pin-and-slot connection 178 with the key-lever 176. Release of either bar 82, 84 causes annular actuation of the typebar 16, but the corresponding spacing movement depends upon which bar is actuated as described below. Restoration of a released bar 82 or 84 and its associated parts is effected as follows:- when a bar is released a vertical slide 124 is moved downwardly by the engagement of the corresponding lever 102' with a projection 130 or 132 on the slide. This movement rotates a spring-supported lever 133 connected by a link to a lever 140 carrying a double cam 146 so as to move the cam into engagement with a continuously-rotating member 150. The consequent rotation of the cam causes the slide 124 to be moved upwardly to bring back the member 82 or 84 to the position in which it is re-engaged by its latch 112 or 114. The character-spacing mechanism for the platen carriage 12 comprises a series of escapement mechanisms each consisting of a ball-race 224, Fig. 6, carrying a rotary tapered ring 220 with teeth 222 around its upper edge. The races are mounted one above the other in a pyramidal structure concentric with a shaft 226. Pivoted to the inside of each ring are two frames 234, 236, connected by a link 239. A fixed dog 242 is mounted on the frame 236 and a dog 240 pivoted at 244 is mounted on the frame 234. The dogs of one ring co-operate with the teeth of the ring immediately below, and normally, due to 'the action of a spring, the dog 240 is in engagement with the teeth and the dog 242 is disengaged. The lowest ring 220 is fixed and the highest ring has attached thereto a pinion 260 meshing with a gear 278, Fig. 1, connected by a one-way drive 22 (see below) to a gear 271 engaging the carriage rack. If one pair of dogs 240, 242 is operated by means of an arm 254 attached to the frame 234, the corresponding ring 220 rotates through one tooth space and carries all the higher rings with it to effect a carriage spacing. If two or more dogs are operated the carriage receives a movement corresponding to the cumulative movements of the corresponding rings. Each escapement imparts a different movement from the others, and in the machine described, by operating the escapements singly or combinations of two or three, a range of carriage movement of from one to forty-three units is obtained. To operate the arms 254, horizontal discs 252 are provided, one for each arm 254. Each disc is connected by vertical rods 258 to a disc 218 engaged from below by a lever 214 connected by a link 213 to the point of a V-shaped lever 210, Fig. 1, pivoted at 212 there being one set of parts 218, 214 213 and 210 corresponding to each escapement. The forward ends of the levers 210 are connected to extensions 206 of U- shaped members 200 pivoted at 202 and situated just to the rear of the keyboard with their horizontal parts adjacent to the front ends of the bars 82, 84. There are seven members 200 shown corresponding to seven escapements, and the bars 82, 84 have one or more projections 88 which, during an operative movement of a bar, engage one or more members 200 and cause actuation of the one or more corresponding escapements to effect the required spacing. If different case types of the same character require different spacing, the arrangement of the projections 88 on the bars 82, 84 of that character will vary. A separate set of seven spacing keys 11 is provided for operating the members 200 independently of the character keys and bars 82, 84. The one-way drive 22 comprises a fine pitch ratchet-wheel 272 engaged by three spring- pressed pawls 273 of slightly-varying length and carried by a plate 275 integral with a sleeve 277 on which the gear 278 is fixed. Thus each tooth of wheel 272 may be held in one of three closelyspaced positions and allows the carriage to be held by the ratchet exactly at any point to which it is adjusted and particularly at the correct starting point after carriage return. According to the Specification as open to inspection under Sect. 91, automatic justification mechanism may be provided. This subjectmatter does not appear in the Specification as accepted.